Noise removal from the image using convolutional neural networks-based denoising auto encoder

The increasing use of digital cameras and imaging devices has led to a surge in daily images, increasing the demand for high-quality images in fields like medical imaging and surveillance. However, noise poses a significant challenge in image processing and analysis, as it degrades image quality and disrupts the preservation of essential features like edges, corners, and textures. Traditional denoising techniques struggle to balance these challenges. In response to this challenge, this thesis introduces a novel approach to image denoising, utilizing a denoising autoencoder based on convolutional neural networks (CNNs). The core objective of this research is to develop a method that effectively reduces noise in digital images while preserving key features. This is achieved through a two-step process involving an autoencoder and a CNN. The initial phase of this process involves categorizing input images into training and testing datasets. This categorization is crucial for the subsequent training and evaluation phases of the model. The training phase employs a denoising autoencoder, a variant of the traditional autoencoder specifically designed for noise reduction. This autoencoder learns to reconstruct noise-free images from their noisy counterparts. The success of this phase is contingent upon the autoencoder's ability to capture the essential features of the images while discarding the noise. Following the autoencoder's training, the denoised images are then fed into a convolutional neural network. The CNN, renowned for its effectiveness in image recognition and processing tasks, further refines the denoised images. It does this by learning hierarchical representations of the data, enabling the extraction of more sophisticated features. The training of the CNN is a critical step in enhancing the overall quality of the denoised images. The testing phase involves evaluating the performance of the proposed system using the test dataset. This phase is pivotal in determining the efficacy of the model in real-world scenarios. The evaluation metrics employed are the Root Mean Square Error (RMSE) and the Peak Signal-to-Noise Ratio (PSNR), both standard in assessing image quality. To facilitate a comprehensive evaluation, the MATLAB programming language was used due to its extensive support for image processing and neural network functionalities. The experiments were conducted on two distinct datasets: the COVID-19 Radiography Database and the SIIM Medical Images Dataset. These datasets were chosen for their relevance in medical imaging, a field where the quality of images is critical. The results of the evaluation demonstrate the superiority of the proposed method over the baseline techniques. On the COVID-19 Radiography (CXR) dataset, the proposed method achieved an 8% improvement in PSNR and a 53% reduction in RMSE compared to the baseline method. Similarly, on the CT Medical dataset, the proposed method outperformed the baseline by 5% in terms of PSNR. These results are indicative of the method's efficacy in not only reducing noise but also in enhancing the overall image quality. One of the key strengths of the proposed approach is its versatility. While the research focused on medical imaging, the method is applicable to a wide range of domains where image quality is critical. Furthermore, the two-step process of using an autoencoder followed by a CNN provides a robust framework for denoising. The autoencoder effectively reduces noise while the CNN enhances the image features, resulting in a synergistic effect that significantly improves the quality of the images. Finally, this thesis presents a novel and effective approach to image denoising, leveraging the strengths of denoising autoencoders and convolutional neural networks. This research contributes significantly to the field of image processing, offering a promising solution to the ever-present challenge of noise in digital images.